Polishing method and material



Dec. 29, 1953 J. F. HARPER POLISHING METHOD AND MATERIAL 2 Sheets-Sheet1 Filed Oct. 14, 1949 INVENTOR JOHN F. HARPER BY [UM ATTORNEY J. F.HARPER POLISHING METHOD AND MATERIAL Dec. 29 1953 2 Sheets-Sheet 2 FiledOct. 14, 1949 FIGLB I N VENTOR JOHN F. HARPER BY /5. MM

ATTORNEY FIG.5

I gan Nu I,"

Patented Dec. 29, 1953 UNITED STATES PATENT OFFICE POLISHING- METHOD ANDMATERIAL John F. Harper, Portland, Conn.

Application October 14, 1949,, Serial N0..12'1,357

(Cl. El- 282.)

Claims.

to as polishing, and which involves scratching or cutting the surfacesof castings or other articles with coarse abrasive particles or gritsand removing or crossing out the coarse or deep scratches or cuts withsuccessively finer scratches made by successively finer grits, and tocoloring, which involves removing or crossing-out the polish or finescratches of the least coarse grits with pumice, Tripoli, rouge orsimilar glossproducing or coloring material.

Heretofore, polishing and coloring generally has been performed bybringing the surfaces to be finished into contact with abrasive wheelsor with belts, buffs or brushes laden with grits, pumice, rouge or thelike and rotating at high speeds.

Numerous problems and disadvantages are encountered with thesepractices, particularly with irregularly shaped articles requiringuniform finishing without loss of shape. The time and labor involved inpresenting the surfaces of an article to buffs carrying successivelyfiner grits even with semi-automatic equipment is high for the simplestshapes and increases rapidly with irregularities in the shape of thearticle to be finished. The automatic and semi-automaticequipment islimited in its use to the finishing of a specific article or type ofarticle and is expensive to design and construct. In addition, thebu'fis, wheels, brushes, belts and the like are worn out rapidly.

These and other disadvantages of known particles are eliminated by thepresent invention which involves feeding flexible or non-rigid abradingmembers, each of which has considerably greater weight than theindividual-grit particles secured to its surfaces, between a pair ofperipherally contacting or closely contiguous buifs or brushes whichrotate'at high speed in opposite directions and throw the abradingmembers against the surface to be abraded. The speed of the abradingmembers coupled with their weight or mass cause the grits to dig intoand scratch the work surface while the flexible yielding character ofthe non-rigid backing or supporting members for the grits, assures thatthe members slide along the work surface and press the grits intocutting or scratching engagement rather than permitting them to bounceand produce a peaning or chiseling action.

The method of the present invention is not to be confused with a sandblasting operation which is usually carried out by feeding abrasiveparticles such as sand. shot or the like into a confined stream of highpressure air and discharging the sand entrained in the air at highvelocity through a nozzle into the surface to be treated. This sandblasting is a cleaning operation in which the particles of sand eifect ahammering or peaning action which roughens and cleans and is the actionwhich the present invention avoids. The particles of sand bounce off orare deflected by contact with the Work piece. They do not slide alongthe surface of the Work piece and follow its contour to produce, despiteirregularities in contour, a continuous scratch or cut. Producing thelatter action with freely moving members is unique with the presentinvention and may be obtained by throwing the abrading particles, grits,pumice, rouge or the like together with a multitude of flexible members,such as pieces of leather, cloth,

' paper, or the like, which slide along rather than bounce off thesurface at which they are impelled at high speed and press the grits orother polishing or coloring particles into polishing or coloringengagement with the work piece as the flexible members slide overthework surface, following closely any irregularities thereof.

'It will be apparent from the foregoing brief statement, that it is anobject of the present invention to provide a method by means of whicharticles requiring polishing or coloring may be polished and coloredreadily and economically and which assures a highly effective anduniform polishing of irregular as well as uniform shapes. This inventionproduces a polish which has been virtually impossible to obtain onhighly irregular surfaces by polishing methods and equipment heretoforeknown and employed, and a polish on plain surfaces more readily andeconomically than by known practices of the art.

A further object is to provide a process in which finishing is effectedby throwing abrasive or coloring particles loosely with, or bonded tomembers of greater size, weight and flexibility than the particles, athigh speed against the surfaces to be polished or colored.

The process may be performed with a polishing apparatus in which thepolishing or coloring. materials are entrained by and thrown frombetween a pair of wheels rotating at high speed in'opposite directionsand wherein the portions of each wheel engaged by the materials are notconnected laterally or circumierentially and, therefore, are not subjectto, or capable of having circumferential or transverse stresses. Moreparticularly, the invention contemplates the use of multiple ply clothwheels or buffs, brushes or the like which do not present laterally orcircum-' ferentially connected peripheral surfaces that resist and arethemselves rapidly mutilated, especially where the surfaces contactedand pressed against abrasive particles are stretched and under tensionstresses. Rather, the buffs. brushes or the like employed in accordancewith the invention, freely receive and accommodate the polishingmaterials and present little if any resistance to the abrasiveparticles. Wear and deterioration of the wheels is negligible.

The cooperating wheels preferably rotate at substantially the same speedso that there is no appreciable relative movement and wearing actionbetween the wheels, or between the wheels and the abrasive, such aswould be present if the wheels rotated at substantially differentspeeds, or if one of the wheels were replaced by a stationary member orshoe.

Although these and other objects and features characteristic of theinvention are set forth in the appended claims, the invention itself, aswell as its objects and advantages, and the manner in which it may bepracticed, may be better understood from the followin description of anillustrative embodiment made with reference to the accompanyingdrawings, in which:

Figure l is a side elevational view partially in section of theapparatus for handling and throwing the polishing or coloring materialsin accordance with the invention;

Fig. 2 is a cross-sectional view taken generally on line 2--2 of Fig. 1;

Fig. 3 is a cross-sectional view, taken on line 3-3 of Fig. 1;

Fig. 4 is an enlarged cross-sectional view of one of the two identicalbuffs shown in Figs. 1-3; and

Fig. 5 is an enlarged perspective view of one form of abrading materialwhich may be employed, in accordance with the invention, in theillustrative apparatus shown in Figs. 1-3.

Referrin to the drawings, there is shown a frame generally designated Ihaving a horizontal table 2 on which is mounted two rotatable buffwheels 1 and 5 that are identical and are built up to a desired width bya number of plies of cloth discs 8 pressed together on shaft l byflanges 8. While each of the buffs d and 5 preferably consists of thesame number of discs 6, the number of discs 5 in the buffs may be variedto increase or decrease the thickness of the buffs and the width of astream of polishing or coloring materials 9 which can be received anddischarged by the buffs in a manner to be hereinafter described.

The buffs d and 5 may be individually and independently rotated inopposite directions with their peripheries adjacent to or in contactwith one another or, as shown in the illustrated embodiment, only one ofthe wheels need be driven, the engagement of driven buff 5 with thefreely rotatable buff 3, either directly or through their mutualengagement with the polishing or coloring materials 5, being suiiicientto rotate the buff 4 at the speed of the driven buff 5.

, The drive for the buds may vary, the one shown bein from an electricmotor it through a belt and pulley variable speed charger, generallydesignated H, which may be adjusted manually by means of hand wheel 12to vary the speed of the buffs while they are rotating.

The polishing or coloring material 9 may be fed directly to the troughformed by the bufis 4 and 5 from a hopper l3 which includes side wallsl4 and front and back walls IS, the lower edges of which conform and areclosely adjacent to, but out of contact with the buffs.

In accordance with the invention, the polishing or coloring material 9consists of a quantity of generally identical members 9a, each of whichis formed of flexible material on which grits or other abrading orcoloring particles 92) are carried. The flexible members 9a may, forexample, be short strips of cloth, rubber, leather, paper or the like,which are mixed or impregnated with grits, pumice, Tripoli, rouge, orother abrading, polishing or colorin particles 9b to provide thefinishing material 9. In the form shown in Fig. 5, the grits Sb arebonded to the flexible body members 9a on its edges as well as onprincipal surfaces, whereas the material shown in Fig. 1 consists ofmembers to and particles 91) loosely mixed together As shown in Fig. 5,the flexible member is a planate body or sheet having top and bottomgenerally parallel plane surfaces the lengths and width of each of whichis many times the side thickness of the body. It also is apparent thatthe polishing particles 9?) are relatively so small that a multitude ofthem may be disposed over the top and bottom plane surfaces and, ifdesired, even over the thin sides of the planate member 9a.

The abrading or colorin particles 91) preferably are of substantiallythe same fineness for any particular batch of material 9. However, itwill be understood that different batches of the material S may beprovided with particles 91) of increasing fineness so that the coarsescratches produced by a first or coarse grade of particles will becrossed out and obliterated by successively finer particles ofsuccessive batches and they, in turn, obliterated by the action of likeflexible members 9a carrying coloring compound or rouge particles ofgreater fineness.

As the material 9 is fed from the hopper l3 it is caught and drawn awayby the rotating buffs 4 and 5, the component discs of which freely yieldto receive and accommodate the material 9 without appreciable wear onthe wheels and, thereafter, discharge the material 9 at high speed in astream against the surface of a workpiece l6. Preferably, the workpieceis suitably chucked so that it may be rotated or otherwise moved topresent successive portions of its surface to the action of the streamof polishing material 9.

As previously pointed out, the members 90. slide over the surface of theworkpiece into its depressions as well as over high points. Theparticles 9b scratch, out, or color and effect a generally uniformaction at all points without distor-ting or obliterating the originalconfiguration of the surface.

Preferably the work surface being polished or colored is angularlydisposed to the stream so as to facilitate sliding of the members 9aover the surface and is close to the line of contact of the buffs 4 and5 from which the stream is discharged. The large surface area of themembers 9a relative to their weight and thickness decelerates the speedof the members so that their velocity and consequently their abradingaction in combinaticn with the particles 9b is less pronounced at adistance from the wheels 4 and 5. As a result, the velocity of thematerial 9 which avoids, as

well as that which strikes and is decelerated by the workpiece, is notas great when it reaches the recovery hopper I! located below theworkpiece and the hopper is not excessively abraded.

From the recovery hopper ll the members 9 may be fed through chute I8 toa bucket hoist 19 which returns the polishing or coloring material 9 tothe feed hopper l3 through a delivery chute 20.

A housing 2| may be provided to enclose the wheels 4 and 5 and theworkpiece l6, accesses to the workpiece being had through an opening 22which may be shielded by a curtain 23 or other suitable means forpreventing the discharge of stray material 9 from the housing.

Although multipleply cloth disc buffs 4 and 5 are employed in theillustrated and described embodiment of the invention, brushes or otherwheels also may be employed. The wheels 4 and 5 preferably are thosewhich can freely receive and accommodate the members 9 with little ifany appreciable wear. However, wheels having connected lateral orperipheral surfaces, in which tension stresses maybe established normalto the pressure exerted by the members 90. when they are between theWheels, are not desirable as deterioration of such wheels may beexcessive.

As previously pointed out, the particles 9b may be loosely mixed with,bonded to, or impregnated in the members 9a. In addition, the inventioncontemplates locating a cake 24 of polishing or coloring compound, as inthe hopper I! or elsewhere, so that the members 9a will strike the cake24 with sufiicient force to replenish their supply of the compoundcontaining the particles 9b before being returned to the feed hopper l3and again discharged by the wheels 4 and 5 against the workpiece Hi. Italso is preferable where the members 911 are formed of cloth to cut themembers on the bias so that the threads are angularly disposed relativeto the edges. Such an arrangement has been found to minimize unraveling.

While the present invention has been more or less specificallyillustrated and described it should be understood that various changesmay be resorted to within the scope of the appended claims, and that thematerials, components and methods may be modified as varying conditionsor finishes may demand.

Having thus described the invention, I claim:

1. The method of polishing a surface of an article which comprisesthrowing at the surface of the article polishing abrasive particles anda di-' 3. The method of polishing described in claim 1 wherein saidpolishing particles and said members are thrown together in a. directedstream at the surface of the article.

4. The method of polishing a surface of an article which comprisesthrowing abrasive particles having minute weight at the surface of thearticle at a velocity at which the individual particles would tend to bedeflected by and to bounce from Said surface and simultaneously throwingadmixed flexible planate sheet members which have many times greaterweight and have a high top surface area to side surface area ratio andwhich cling to and slide over said surface while pressing said particlesagainst the surface.

5. The method of polishing described in claim 4 and wherein theparticles are carried by said members. I

6. The method of polishing described in claim 5 and wherein the materialconsisting of said particles and said members is collected and rethrownat said surface and the supply of particles carried by said members arereplenished between successive throwings.

7. The method described in claim 5 wherein the particles are replenishedby impact of the stream of said members with a supply of said particles.

8. The method of polishing a surface of an article which consists inmechanically propelling a batch of material containing polishingparticles and larger planate flexible members having large top surfaceto edge surface area in a directed stream at high speed against saidsurface.

9. Finishing material consisting of a batch of generally like flexibleplanate sheet members each of length and width many times greater thanthickness and of finishing particles and wherein the length and width ofthe flexible planate sheet members are each many times the thickness ofthe members and the finishing particles are of a substantially uniformdegree of fineness.

l0. Polishing material as described in claim 9 and wherein the finishingparticles are substantially uniformly distributed over and bonded to thesurface area and side edges of the flexible planate members.

JOHN F. HARPER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,352,598 Hart Sept. 14, 1920 1,588,768 Moulton June 15, 19262,092,962 Fay et a1 Sept. 14, 1937 2,225,482 Mulvany Dec. 17, 19402,421,806 Perry June 10, 1947 2,426,072 Wall et a1. Au 19, 1947

